[PATCH AUTOSEL 6.14 345/642] bpf: arm64: Silence "UBSAN: negation-overflow" warning
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DORMANTno replies
REVIEWED: 4 (4M)
From: Sasha Levin <sashal@kernel.org>
Date: 2025-05-05 22:28:09
Also in:
bpf, lkml, stable
Subsystem:
arm64 port (aarch64 architecture), bpf jit for arm64, bpf [general] (safe dynamic programs and tools), the rest · Maintainers:
Catalin Marinas, Will Deacon, Daniel Borkmann, Alexei Starovoitov, Puranjay Mohan, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Linus Torvalds
1 review trailer.
From: Song Liu <song@kernel.org> [ Upstream commit 239860828f8660e2be487e2fbdae2640cce3fd67 ] With UBSAN, test_bpf.ko triggers warnings like: UBSAN: negation-overflow in arch/arm64/net/bpf_jit_comp.c:1333:28 negation of -2147483648 cannot be represented in type 's32' (aka 'int'): Silence these warnings by casting imm to u32 first. Reported-by: Breno Leitao <leitao@debian.org> Signed-off-by: Song Liu <song@kernel.org> Tested-by: Breno Leitao <leitao@debian.org> Link: https://lore.kernel.org/r/20250218080240.2431257-1-song@kernel.org (local) Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> --- arch/arm64/net/bpf_jit_comp.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index 8446848edddb8..7409c8acbde35 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c@@ -272,7 +272,7 @@ static inline void emit_a64_add_i(const bool is64, const int dst, const int src, { if (is_addsub_imm(imm)) { emit(A64_ADD_I(is64, dst, src, imm), ctx); - } else if (is_addsub_imm(-imm)) { + } else if (is_addsub_imm(-(u32)imm)) { emit(A64_SUB_I(is64, dst, src, -imm), ctx); } else { emit_a64_mov_i(is64, tmp, imm, ctx);
@@ -1159,7 +1159,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, case BPF_ALU64 | BPF_SUB | BPF_K: if (is_addsub_imm(imm)) { emit(A64_SUB_I(is64, dst, dst, imm), ctx); - } else if (is_addsub_imm(-imm)) { + } else if (is_addsub_imm(-(u32)imm)) { emit(A64_ADD_I(is64, dst, dst, -imm), ctx); } else { emit_a64_mov_i(is64, tmp, imm, ctx);
@@ -1330,7 +1330,7 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, case BPF_JMP32 | BPF_JSLE | BPF_K: if (is_addsub_imm(imm)) { emit(A64_CMP_I(is64, dst, imm), ctx); - } else if (is_addsub_imm(-imm)) { + } else if (is_addsub_imm(-(u32)imm)) { emit(A64_CMN_I(is64, dst, -imm), ctx); } else { emit_a64_mov_i(is64, tmp, imm, ctx);
--
2.39.5